Determination of silicon in serum and urine by electrothermal atomic absorption spectrometry

A sensitive, simple and accurate method for the routine determination of trace silicon in serum and urine by Zeeman electrothermal atomic absorption spectrometry is described.,The samples are directly determined after 20-fold dilution of serum and 100-fold dilution of urine. No L'vov platform is used. The signal enhancement of silicon atomization in pyrolytic graphite coated graphite tubes is achieved by using a mixture of calcium chloride and lanthanum nitrate as chemical modifier. The interferences arising from the biological matrices have been eliminated by the addition of ammonium dihydrogenphosphate in the sample solutions. The aqueous calibration curve is linear to at least 300 mu g l(-1), the characteristic mass is 37 pg (integrated absorbance signal), whereas the detection limit (3SD) is 1.5 mu g l(-1) for silicon in both diluted serum and urine samples. The recoveries of silicon added to the diluted samples are 101 +/- 1.8% for sera and 98.2 +/- 3.5% for the urine specimens, independent of the dilution ratio. The silicon measurement results for the serum and urine from healthy adults and for the serum from the patients with chronic renal failure on hemodialysis are presented.